Having been in engineering for 40 odd years I would echo the comments above re 'Nyloc' type nuts being 'once only' fastenings in any critical application.
There is an added problem if 'Nyloc' type nuts are used where they may be subjected to high temperatures - ie high enough to melt the nylon insert!
I may be a bit of a luddite, but wire or split pins on castelated nuts are still far safer than any insert type nut. They can be inspected visually and are there or not unlike inserts which can be degraded without showing any signs.
Tin hat on in case the manufacturers take offence!!